Intel 64 and IA-32 Architectures Software Developers Manual Volume 3B, System Programming Guide Part 2

Table Of Contents
Vol. 3 F-5
APIC BUS MESSAGE FORMATS
priority arbitration, drives cycle 33. An error in cycle 33 will force the sender to
resend the message.
F.2.3 APIC Bus Status Cycles
Certain cycles within an APIC bus message are status cycles. During these cycles the
status flags (A:A) and (A1:A1) are examined. Table F-4 shows how these status flags
are interpreted, depending on the current delivery mode and existence of a focus
processor.
Table F-4. APIC Bus Status Cycles Interpretation
Delivery
Mode
A Status A1 Status A2 Status Update
ArbID and
Cycle#
Message
Length
Retry
EOI 00: CS_OK 10: Accept XX: Yes, 13 14 Cycle No
00: CS_OK 11: Retry XX: Yes, 13 14 Cycle Yes
00: CS_OK 0X: Accept
Error
XX: No 14 Cycle Yes
11: CS_Error XX: XX: No 14 Cycle Yes
10: Error XX: XX: No 14 Cycle Yes
01: Error XX: XX: No 14 Cycle Yes
Fixed 00: CS_OK 10: Accept XX: Yes, 20 21 Cycle No
00: CS_OK 11: Retry XX: Yes, 20 21 Cycle Yes
00: CS_OK 0X: Accept
Error
XX: No 21 Cycle Yes
11: CS_Error XX: XX: No 21 Cycle Yes
10: Error XX: XX: No 21 Cycle Yes
01: Error XX: XX: No 21 Cycle Yes
NMI, SMI, INIT,
ExtINT,
Start-Up
00: CS_OK 10: Accept XX: Yes, 20 21 Cycle No
00: CS_OK 11: Retry XX: Yes, 20 21 Cycle Yes
00: CS_OK 0X: Accept
Error
XX: No 21 Cycle Yes
11: CS_Error XX: XX: No 21 Cycle Yes
10: Error XX: XX: No 21 Cycle Yes
01: Error XX: XX: No 21 Cycle Yes